Internal-combustion hot-air heater



1948- 1.. A. WILLIAMVS, JR 2,457,513

INTERNAL-COMBUSTION HOT AIR HEATER Filed Feb. 26, 1945 2 Sheets-Sheet 1 Dec. 28, 1948. L. A. WILLIAMS, JR 2,457,513

INTERNAL-COMBUSTION HOT AIR HEATER I Filed Feb. 26, 19 4s 2 sheeis-sheet 2 Patented Dec. 28, 1948 UNITED OFFICE 2,454,513 I wrenmnecormusrron no; rimaran Lyn A- Wi11iams .J.r-. hfie dilfl es i eer t stewart wfiiiner Corporation, 'Qhieagofllln a corporation of Virginia. .hhn ea ieh-Ee hher e we hummer "3 file m M i ve t on e a e to heaters-and here 12er i l r t a e e he in na eem hstieh type.

' In heaters of the internal combustiontype, it is commo to ha e o ts o mbus n as directly from a combustion chamber intoione end of a heat exchanger over which ventilating air is directed. That portion of the. heat exchanger which is first contacted by ,the hot gases, ssu n om the m us qh hamber sh eted to a much higher temperature than is the re.- mei de 0f he heat exe hgeh w t e r ul that this portion of the heat exchanger is some.- times burned out or temperature stresses and st in a et u i th a exe eh er whic o en it hf end. pai t efi ehey he eh Jee e zm hv-eh iehi o o er me th se listedvanta e of th prior a t h a e s- AhQthe ob e t m in n on is to va y the rate of heat transfer between the hot products oi combustion and the walls confining these gases by varying the velocity of flow of these gases in difierent parts. of the heater.

Another object of my invention is to 'vary the rate of heat transfer between walls heated by the hot gases of combustion and ventilating air directed over these walls by varying-the velocity-oi flow of the ventilating air in different parts of the heater.

Another object of my invention is to var-y the velocities of flow of fluids passing through the heater in different portions of the heater to provide a more uniform heating of the metal parts of the heater.

Another object of my invention, is to provide a heater wherein walls'separating the hot prod.- ucts of combustion from the ventilating air are maintained at b ntia ly h iiqhh tem era re eh t the heeteh ehet eh e iee f m i ve tion i to xe isie a te he ei e redn ts i .eemhlis eh and nti at n a r flow in ep e reet hs ehfl where n a hhs ehtiel un form rat e hea trans re the pr duc e eembh t to the vent latin ai is ma a ned re heht th sh he hee r- Other objects and advantages will become ap.-., parent as the description proceed It; the drewihee (01. tee-n6) 2 7 E i qhe tiidih i e t ena v e Qf, a. hea r niheeiyihe h inventiqn;

T e-lie .e e. rse s ti e View taken on the l ne-2+2; 9 F e- 1; ant

Fieis e ehd levet on l kin re h thel t inrrrg. 1.

The ete shewh in Fi 1, a d 3 ha a gene a ly y iheriel easing H r vi ed with a e e ih et en ada d t be conne ed to a ram, blower, or other suitable source of. air ppl e t 9f th a n e i the nl fletts ehethwis threheh e tub 4 and nte s the tapered inlet of a pipe L8 leading to a Carburetor 2D. The carburetor is provided with the usual float bowl .22 connected by pipe 2.4 to the u ta l sehree 9 uel .suppl The hea bowl 2;? furnishes fuel to a jet 26 located in the h e ef the t r tube 2 whi h d l ver a mixture of fuel and air to an induction tube 30. I

The inductio tube :30 s fera of miterm ei ht te and x ends hro h the a n :9 end ente well 1 o a m u t on cham e fe lhe ih twe the i dr ca shee me eate Welly. he a ey ndr e sh et metal in wellifi- .ihdhe ihn tube 3.0 ha a r h ating, portion 518 which lies, within the combustion chain er 3 4. and is curved abont the axis thereof. T hjs indnction tube terminates in an outlet end positioned to discharge combustible mixture. an entiall to theennula ombustio chamber t9 ereetea ring of. lame there as ri ed ehsi c aimed. n the e el e app c t en o l i enry J. pehl. Mcqollnm, Serial No. 477,080, filed 2. 13 .3,. Patent No. 2, ,613 isshe ee ihhe ,0,. 13411,-

.ehd einmi ture de r to h comhstiee he h e by the indu i n hbe 3 0 i ignited by an electrical igniter 42 (Fig. 3). The heteesee. resul in rexn he c mbustion in t on chamber, pass from the righthand his hi thisehembe int a tap r d mfl p s.-

setee A. ..f.ermed.he wee e he sheet metal Wells. 45- nd 4.8, Whieh c ns tu e ex sions f combu tion chamber walls. 32 and 36, respectively. As the hot sesflow leng hwi o he a d passage, .44, they aremined with secondary air ehter e nasseee b way et a i u a eries O hehine eflg preferably formed by d spla n ton ues 5.1,,andrr neihe thes o ue a sheh .ahele, t a ehte ihe, ...h

3 passage 44 is traveling in the same general direction as the gases therein.

As the hot gases travel lengthwise of the passage 44, these gases give up their heat to the: walls 46 and 48 thereof. Because the cross-section of the passage 44 decreases toward the outlet 54 through which the cooled gases are discharged to atmosphere, the velocity of flow of the gases continually increases as these gases approach this,

combustion to the wall 46 and combustion cham-' ber wall 32 are absorbed by the ventilating air.

flowing through an annular passage 56 formed between these walls and the casing Ill. The tapered wall 46 causes the cross-section of this pas-,

sage 56 to decrease from right to left so that the ventilating air flowing through this passage is flowing at a faster velocity as it approaches the lefthand end of the passage and tends to absorb more heat from the lefthand end of the wall 46, The reverse tapering of the gas passage 44 and of the ventilating air passage 56 on opposite sides of the wall 46 are designed to maintain this wall at substantially uniform temperature throughout its length-to prevent overheating of any particular portion of this wall, to prevent the creation of temperature strains and stresses therein and to provide maximum efilciency of operation of the heater.

The heat absorbed by the tapered wall 48 and inner wall 36 of the combustion chamber is absorbed by ventilating air flowing through the annular passage 58 formed between these walls and the tube l4. This passage 58 decreases in crosssection from right to left, as viewed in Fig. 1, so that the velocity of air flow therethrough progressively increases despite the diversion of a small amount of secondary air through the openings 50 and into the gas passage 44. The differing velocities of flow of the hot gases on one side of the tapered wall 48 and of the ventilating air on the opposite side thereof serve to maintain this wall at substantially uniform' temperatures throughout and thus prevent excessive heating of any portion of this wall, prevent the'formation of undue temperature stresses and strains therein, and promote maximum heat transfer through this wall.

The righthand ends of the ventilating air passages 58 and 58 are in open communication with the air inlet [2 and the lefthand ends of these passages discharge into the lefthand end of the casing Ill. This end of the casing may direct the ventilating airinto an airplane cabin or other space to be heated or into a duct system having selected outlets located in the same or different spaces.

The combustion air flowing to the carburetor 20 through the tube l4 absorbs heat from the walls of this tube to facilitate vaporization of the fuel mixed with this air. Additional preheating of the combustible mixture is provided by the parent that the velocity of flow of the products of combustion increases as these products move farther and farther away from the combustion chamber, whereas the ventilating air travels faster and faster as it approaches the combustion chamber and these varying velocities of gas and air flow are utilized to improve the efficiency of the heater and to eliminate temperature stresses and strains and burn out portions. vantages are accomplished by a simple structure which is light in weight and which may be easily and economically manufactured of conventional materials .toproduce a'compact heater having a high heat output and capable of use with light or heavy fuels.

While I have illustrated and described a single embodiment of my invention, my invention is not limited to the details shown and described, but

may assume numerous other forms and the scope of my invention is defined in the following claims.

I claim: 1.-A heater of the class described, comprising a cylindrical casing having one end adapted to mentioned air passage, a carburetor receiving a supply of combustible air from said tube, means forming a combustion chamber communicating with said tapered gas passage, and an induction tube connecting said carburetor with said combustion chamber.

2. A heater of theclass described comprising a tubular casing having one end connected to a source of air supply, a tapered tubular'wall coaxially disposed in said casing and cooperating therewith to'form a ventilating airpassage communicating with said source and tapering continuously therefrom, a second tubular wall co-' axially disposedwithinsaid first mentioned wall and tapered in the opposite direction to form a gas passage tapered oppositely to said ventilating air passage, an additional tubular member coaxially disposed within said second tubular wall and cooperating therewith to form a second ventilating air passage tapered in the same direction as said first mentioned air passage and also com municating with said source, and means forming a combustion chamber communicating with the larger end of the tapered gas passage. 7

.3. Aheaterof the class described comprising means forming a combustion chamber, heatexchange means receiving hot products of combustion from said combustion chamber, and means for directing ventilating air over said heat ex change means toward the combustion chamber, said combustion chamber] forming means and said heat exchange means consisting of walls forming .a single relatively long passageway for conveying the products of combustion, said passageway tapering continuously with increased distance from said combustion chamber to cause the products of combustion to flow therethrough with accelerating velocity, and said ventilating air directing means comprising a shell concentric with said passageway and forming with one of said passageway'forming wallsfa ventilating air conduit decreasing continuously in cross sec- These ad- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 8,487 Ingalls Nov. 4, 1851 1,406,111 Tuck Feb. 7, 1922 Number Number Name Date Lippert Jan. 11, 1927 Bolling et a1 Nov. 6, 1928 Cramer Apr. 22, 1930 Noblitt Nov. 18, 1930 Conejos Mar. 31, 1931 LeGrand Sept. 20, 1932 Grill et a1 Dec. 27, 1938 Warren et a1. Jan. '7, 1941 Frantz Dec. 30, 1941 FOREIGN PATENTS Country Date Switzerland Oct. 31, 1903 

